Preparation of cation exchange material from coal



2,693,453 Patented Nov. 2, 1954 PREPARATION OF CATION EXCHANGE MATERIAL FROM COAL Martinus L. Goedkoop, Geleen, Netherlands, assignor to De Directie van de Staatsmijnen in Limburg, Handelend voor en namens de Staat der Nederlanden, Heerlen, Netherlands No Drawing. Application March 16, 1951,

Serial No. 216,097

Claims priority, application Netherlands March 21, 1950 5 Claims. (Cl. 252-179) This invention relates to the manufacture of cation exchange materials from carbonaceous solid substances, such as coal, semi coke, precarbomzed peat and lignite.

FIELD OF INVENTION It has been found that cation exchange materials of a very useful nature can be prepared in a rather simple manner from carbonaceous solid substances, such as bituminous coal, anthracite and precarbonized lignite and peat or the like, by heating the carbonaceous material in oxygen or in a free oxygen-containing gas at a temperature within the range of 80 to 450 C. and then hydrolyzing the reaction product in a mildly alkaline medium. Such a process is disclosed in copending patent application, Ser. No. 177,764, of Martinus L. Goedkoop, filed August 4, 1950.

This new type of operation constitutes a decided improvement over the previously known methods of treating carbonaceous materials to obtain cation exchange materials using dehydrated agents, such as concentrated sulfuric acid. Thus, in contrast to the older methods, the new procedures eliminate loss of valuable products and reactants and produce cation exchange materials which are more uniform in size. Nevertheless, these new procedures have certain aspects which can stand improvement. For example, the heating period required in the new operations is quite long in some cases, thus adding to the expense of the operations and possible diminution in yield.

OBJECTS A principal object of this invention is the provision of new improvements in the manufacture of cation exchange materials from solid carbonaceous substances. Further objects include:

(1) The provision of such procedures which make possible the formation of cation exchange materials of relatively high activity, capable of regeneration after use many times, and of desirable uniform particle size.

(2) The provision of improvements in the method of making cation exchange materials by heating carbonaceous solid substances in oxygen-containing gases and then hydrolyzing the reaction product in an alkaline medium, whereby the heating period is greatly shortened.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

GENERAL DESCRIPTION These objects are accomplished according to the present invention by a process which comprises heating a subdivided solid carbonaceous substance in a stream of gas containing free oxygen and also containing a nitrous vapor to a temperature between 80 and 450 C. and then hydrolyzing the reaction product in an alkaline medium.

Although the process may be carried out as a batch operation, it is preferably conducted as a continuous process with recycling of the nitrous vapors. It is also preferable to circulate heating and treating gas at such velocities that the subdivided carbonaceous material is fluidized by the gas stream in the reaction vessel during the heating operation.

EXAMPLES A more complete understanding of the new procedures of this invention may be had by reference to the follow ing examples of actual operations in accordance with the invention.

Example I This example illustrates the production of a cation exchange material in accordance with this invention.

In a fiuidizing tube (diameter 5 cm.), 200 g. of semianthracite (grain size 0.3 to 1.0 mm.) were heated in a fluidized state for 22 hours at a temperature of 300 C.

by means of a hot air stream which contained nitrous vapors as follows:

15 litres air mixed with 1 litre nitrous vapors were passed per minute into the fluidizing tube, the nitrous vapors being the final discharge gas obtained in the manufacture of nitric acid.

The reaction product was treated for 30 minutes with 3 litres of a boiling sodium hydroxide solution (1 N). After being filtered, the hydrolyzed product was rinsed with distilled water. The weight of the dried reaction product was about equal to that of the starting material.

Example 11 This example illustrates the use of the cation exchange material produced in Example I for the softening of tap .Water and the repeated regeneration of the cation examount of water passed until the cation exchange maas calcium oxide).

terial broke down (until the outflowing water contained calcium) was measured.

After 2.9 litres tap water had passed, the cation exchanger proved to have broken down. Subsequently, the cation exchange material was regenerated by passing a 10% sodium chloride solution at a rate of 1 to 2 ml. per minute through the bed of material. After 300 ml. of the sodium chloride solution had been passed, the regeneration liquor contained 330 mg. calcium (calculated After being rinsed with distilled water, the ion exchange material could be re-used.

After this first regeneration, the cation exchange material broke down after 2.1 litres tap water had passed.

After a second regeneration, which was carried out in the above manner (the regeneration liquor contained 320 mg. calcium oxide), the ion exchange material broke down after 2.1 litres tap water had passed.

After a third regeneration (the regeneration liquor contained 335 mg. calcium oxide), the breakdown was again observed after 2.1 litres water had passed.

In the fourth regeneration, the treatment with 300 ml. sodium chloride solution (the regeneration liquor contained 300 mg. calcium oxide), was followed by a further regeneration with 300 ml. hydrochloric acid (1 N) (the regeneration liquor contained mg. calcium oxide).

Now, the breakdown occurred after 2.5 litres tap water had passed. The fifth regeneration was carried out with 300 ml. hydrochloric acid (1 N) when the regeneration liquor proved to contain 340 mg. calcium oxide.

DETAILED DESCRIPTION The term nitrous vapors as employed in this specification and in the appended claims is intended to denote any gas-or vapor-containing nitrogen in combination with oxygen, such as nitric acid vapors or other gases containing nitrogen oxides, particularly those containing nitric oxide. The nitrous vapors, which in the manufacture of nitric acid are obtained as a final gas and which are usually discharged through the stack as a valueless product, have proved tobevery suitable for the process according to theinvent-ion. 1

The amount of the nitrous vapors admixed is not material, but it is preferred to use only small amounts of nitrous. vapors,, e. g., less than. 1.0% by volume. of the; oxidizing gas mixture, because these. small. amountsare suificient to give good results. Larger amounts of nitrous vapors may be used even to the extent of heating the starting material-v ina. medium which; largely consists of. nitrous vapors. With these high concentrations, however, there is. the formation. of reactionproducts of a lower molecular weight to be taken into account.

The process according tothe invention is carried out in an analogous manner, as has beenset forth in the aforementioned application and; it is desirable to maintain the starting material in a fluidized state whilebeing heated. in the oxidizing gas. v

The: nitrous vapors contained in' the discharged. re-

action; gases maybe refused so that'the-process according to' the invention can be carried out' as a cyclic process; the nitrous vapors belng regenerated 1n' the Well-known manner; for example-with sulfuric acid;

As indicated, the solid carbonaceous substances'should be heated'toa temperature between 80arid:fl50'' C. For most desirable results, giving a product having the smallest amount of soluble components and the highest cation. exchange activity, temperatures between 220 and 350 C..

should be used.

The length of time of heating and contact of' the carbonaceous substances with the oxygen and nitrous vaporcontaining gas stream will depend primarily upon the temperature employed and the nature of the carbonaceous material being treated. Hence, this will vary from case to' case, but under most ordinary circumstances, it'has been found thata time between 8 and 96 hours is most desirable.

The amount of gas used in' the process is governed to a. large extent by' the nature'of the apparatus used in the process, heat losses, and the like, and: is generally controlled so as to maintain the temperature of the carbonaceous substances within the range indicated above. However, in the preferred type of operation, a suificient velocity in: the flow of the treating gas should be maintained'soas to-fiuidize the particles of carbonaceous substances and, here again, the exact numerical values on volume andflow will. depend upon the apparatus and also the density and size of the carbonaceous substances.

The carbonaceous substancesv under treatment should be subdivided, preferably to aunifonn size.

typeof product has been found to be obtained when a particle size between 0.1 and 1' mm. is used.. This size is also especially useful. when the fiuidizing operation is employed.

Although it has been found that some carbonaceous. solid substances are more satisfactorily employed. in. the process than others, the operationis. usable, generally with all suchmaterials as coal,,either bituminous or anthracite, semi-coke, petroleum coke and precarbonized lignite or precarbonized peat; However, the preferred substances include semi-anthracite and' low. volatile bituminous coal.

After the heatingstep is terminated, the. reactionproduct is subjected to hydrolysis in an alkaline medium.

The exact degree of subdivision is not critical, but the most useful Many materials can be used to form the alkaline medium,

suchas-the-salts-of weak acids, for example, metal car- CONCLUSIQNS Through the use of the new procedures, as described above, it is possible to-mahe cation exchange materials cheaply and easily. fromreadily available basic materials, such as coal, semi-coke, precarbonized lignite or precarbonized peator thelike; Theproductsare-obtained in desirable. size. and asimple manner. Oneof. the mainv advantages. der-ivedby these new improvements is the reduction in time of heatingrequired to make the exchange materials; which may be two or three times as short as the heating periods required where these new improvements .are .not. emp loyed.

I claim:

1.. Aprocessfor the manufacture-of cation exchange materialv which comprisesheating, in a; medium. of a free oxygen-containing; gas containing nitrous vapor in an amount up to- 10% by volume and; at atemperature-withe- 1n the range-of from 220 to=350 Q..coal;which=is ox-i-- dizable. but not completely; decomposable under the con.- (lltlOl'lS employed-and; which is.of about 0.1 to' 1 mm.

particle size, continuing said heatinguntil saidamaterialv isoxiclized,subsequently hydrolzing the oxidizedproduct by treatment thereof with. at hot: aqueous. strongly alkaline solution and thereafter separatingithe hydrolyzed product from said solution, the time of heating the. initial coal beingsuchthatthe particle size: of. the cation exchanger. 18. substantially the same graim size as. that: of the starting; matenial.

2-..Tl1e:processoficlaim. 1, wherein the particles are fluidized. during: said: heating in: said gas stream.

3.. The-.processoi claim. 1,. wherein the coal is semi anthracite coal.

4.. The: process. ofclaim; 1;. wherein: the" coal is bituminous coal.

5. The process of claim; 1'-wherein hydrolysis is ellected by treating said productwith a2 to 5% aqueous. sodium hydroxide solution.

References Cited in the fileofj'this patent UNITED STATES PATENTS- Number Name Date 2,309363' Urbainzetal. Jan. 26, 1943- 2,338,634 Fuchs Jan. 4, 1944 FOREIGN PATENTS Number Country Date 547,580. Great: Britain, Sept. 2, 1942 

1. A PROCESS FOR THE MANUFACTURE OF CATION EXCHANGE MATERIAL WHICH COMPRISES HEATING, IN A MEDIUM OF A FREE OXYGEN-CONTAINING GAS CONTAINING NITROUS VAPOR IN AN AMOUNT UP TO 10% BY VOLUME AND AT A TEMPERATURE WITHIN THE RANGE OF FROM 220* TO 350* C. COAL WHICH IS OXIDIZABLE BUT NOT COMPLETELY DECOMPOSABLE UNDER THE CONDITIONS EMPLOYED AND WHICH IS OF ABOUT 0.1 TO 1 MM. PARTICLE SIZE, CONTINUING SAID HEATING UNTIL SAID MATERIAL IS OXIDIZED, SUBSEQUENTLY HYDROLYZING THE OXIDIZED PRODUUCT BY TREATMENT THERETO WITH A HOT AQUEOUS STRONGLY ALKALINE SOLUTION AND THEREAFTER SEPARATING THE HYDROLYZED PRODUCT FROM SAID SOLUTION, THE TIME OF HEATING THE INITIAL COAL BEING SUCH THAT THE PARTICLE SIZE ON THE CATION EXCHANGER IS SUBSTANTIALLY THE SAME GRAIN SIZE AS THAT OF THE STARTING MATERIAL. 